From: Bryan Reece <reece@taz.nceye.net>
Date: Thu, 28 Nov 1996 11:39:46 -0800 (PST)
To: deviant@pooh-corner.com
Subject: Re: Is /dev/random good enough to generate one-time pads?
In-Reply-To: <Pine.LNX.3.94.961128152339.1435A-100000@random.sp.org>
Message-ID: <19961128194007.12992.qmail@taz.nceye.net>
MIME-Version: 1.0
Content-Type: text/plain


   Date: Thu, 28 Nov 1996 15:31:28 +0000 (GMT)
   From: The Deviant <deviant@pooh-corner.com>

   On Wed, 27 Nov 1996, Igor Chudov @ home wrote:

   > Subj sez it all.
   > 
   > Thank you.
   > 
   > 	- Igor.

   Yes, as a matter of fact it is.  /dev/random is based on an entropy pool
   taken from hardware interrupts and such, thus is a RNG, not a PRNG (thats
   right IPG, Linux uses hardware to get random numbers... imagine that!).
   /dev/urandom is, however, a PRNG...

Only if you try to pull out more bits than you can get from /dev/random.

Note that /dev/random on a single-user system doesn't generate bits
fast enough to be practical for OTP generation (try od -tc1
/dev/random sometime; you'll get about 512 bytes if you haven't used
it lately, then reads will block until enough unpredictable things
happen ).  Of course, you can add more randomness sources.

How good a source would a radio or diode noise source connected to the
parallel port's IRQ input be?  It certainly sounds like it would be
cheap enough.